1 files changed, 63 insertions, 0 deletions
diff --git a/m4/realloc.m4 b/m4/realloc.m4
new file mode 100644
index 0000000..86e57c2
--- /dev/null
+++ b/m4/realloc.m4
@@ -0,0 +1,63 @@
+# realloc.m4 serial 26
+dnl Copyright (C) 2007, 2009-2022 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+# This is adapted with modifications from upstream Autoconf here:
+# https://git.savannah.gnu.org/cgit/autoconf.git/tree/lib/autoconf/functions.m4?id=v2.70#n1455
+AC_DEFUN([_AC_FUNC_REALLOC_IF],
+[
+  AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
+  AC_CACHE_CHECK([whether realloc (0, 0) returns nonnull],
+    [ac_cv_func_realloc_0_nonnull],
+    [AC_RUN_IFELSE(
+       [AC_LANG_PROGRAM(
+          [[#include <stdlib.h>
+          ]],
+          [[void *p = realloc (0, 0);
+            int result = !p;
+            free (p);
+            return result;]])
+       ],
+       [ac_cv_func_realloc_0_nonnull=yes],
+       [ac_cv_func_realloc_0_nonnull=no],
+       [case "$host_os" in
+          # Guess yes on platforms where we know the result.
+          *-gnu* | freebsd* | netbsd* | openbsd* | bitrig* \
+          | gnu* | *-musl* | midnightbsd* \
+          | hpux* | solaris* | cygwin* | mingw* | msys* )
+            ac_cv_func_realloc_0_nonnull="guessing yes" ;;
+          # If we don't know, obey --enable-cross-guesses.
+          *) ac_cv_func_realloc_0_nonnull="$gl_cross_guess_normal" ;;
+        esac
+       ])
+    ])
+  AS_CASE([$ac_cv_func_realloc_0_nonnull], [*yes], [$1], [$2])
+])# AC_FUNC_REALLOC
+
+# gl_FUNC_REALLOC_GNU
+# -------------------
+# Replace realloc if it is not compatible with GNU libc.
+AC_DEFUN([gl_FUNC_REALLOC_GNU],
+[
+  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+  AC_REQUIRE([gl_FUNC_REALLOC_POSIX])
+  if test $REPLACE_REALLOC_FOR_REALLOC_GNU = 0; then
+    _AC_FUNC_REALLOC_IF([], [REPLACE_REALLOC_FOR_REALLOC_GNU=1])
+  fi
+])# gl_FUNC_REALLOC_GNU
+
+# gl_FUNC_REALLOC_POSIX
+# ---------------------
+# Test whether 'realloc' is POSIX compliant (sets errno to ENOMEM when it
+# fails, and doesn't mess up with ptrdiff_t overflow),
+# and replace realloc if it is not.
+AC_DEFUN([gl_FUNC_REALLOC_POSIX],
+[
+  AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
+  AC_REQUIRE([gl_FUNC_MALLOC_POSIX])
+  if test $REPLACE_MALLOC_FOR_MALLOC_POSIX = 1; then
+    REPLACE_REALLOC_FOR_REALLOC_POSIX=1
+  fi
+])